I want to read data from Firebase but Log.d("Uservalue", ""+value); return null for me, what should I do?
MainActivity.java：
FirebaseUser user = mAuth.getCurrentUser();
DatabaseReference myRef = FirebaseDatabase.getInstance().getReference("USERS").child(user.getUid());
User user1 = new User(user.getEmail(), user.getDisplayName(), user.getUid(), user.getPhotoUrl().toString());
/* write to firebase database */
myRef.setValue(user1);
/*read*/
myRef.child(user.getUid()).addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
User value = dataSnapshot.getValue(User.class);
Toast.makeText(MainActivity.this, "User", Toast.LENGTH_SHORT).show();
Log.d("Uservalue", ""+value);
}
#Override
public void onCancelled(DatabaseError databaseError) { }
});
User.java：
public class User{
private String email;
private String id;
private String imgurl;
private String name;
public User(){
// Default constructor required for calls to DataSnapshot.getValue(User.class)
}
public User(String email, String name, String id, String imgurl) {
this.email = email;
this.id = id;
this.imgurl = imgurl;
this.name = name;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getname() {
return this.name;
}
public void setname(String username) {
this.name = username;
}
public String getImgurl() {
return imgurl;
}
public void setImgurl(String imgurl) {
this.imgurl = imgurl;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
}
And my firebase data：
And Logcat return null
020-06-03 17:53:12.810 8720-8720/com.example.chatapp D/Uservalue: null
Can anyone help me? Thank you.
And then
I want to ask a question, why User value = dataSnapshot.getValue(User.class); know the name in firebase = name in User, the email in firebase = email in User ......, so that I use value.getName() can get my name's data.
The following call to setValue():
myRef.setValue(user1);
It's an asynchronous operation. So if you want to use (read) that data, you should wait until the write operation is completed. So please check the following lines of code:
uidRef.setValue(user1).addOnCompleteListener(new OnCompleteListener<Void>() {
#Override
public void onComplete(#NonNull Task<Void> task) {
if (task.isSuccessful()) {
String uid = FirebaseAuth.getInstance().getCurrentUser().getUid();
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference uidRef = rootRef.child("USERS").child(uid);
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
User user = dataSnapshot.getValue(User.class);
Log.d("TAG", user.getName());
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
Log.d("TAG", databaseError.getMessage()); //Don't ignore errors!
}
};
uidRef.addListenerForSingleValueEvent(valueEventListener);
}
}
});
Your myRef is already on USERS/$uid node. So change your ValueEventListener to
myRef.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot)
{
User value =
dataSnapshot.getValue(User.class);
Toast.makeText(MainActivity.this, "User",
Toast.LENGTH_SHORT).show();
Log.d("Uservalue", ""+value);
}
#Override
public void onCancelled(DatabaseError databaseError) { }
});
Edit: Or change your Database Reference to
myRef=FirebaseDatabase().getInstance(). getReference("USERS");
myRef.child(user.getUid).setValue(your data);
myRef.child(user.getUid).addValueEventListener(//the rest are same
);
Your myRef is already pointing to your user node
DatabaseReference myRef = FirebaseDatabase.getInstance().getReference("USERS").child(user.getUid());
You are trying listen to another branch of your user node by mentioning uid
myRef.child(user.getUid()).addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
User value = dataSnapshot.getValue(User.class);
Toast.makeText(MainActivity.this, "User", Toast.LENGTH_SHORT).show();
Log.d("Uservalue", ""+value);
}
#Override
public void onCancelled(DatabaseError databaseError) { }
});
Change this code to this
myRef.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
User value = dataSnapshot.getValue(User.class);
Toast.makeText(MainActivity.this, "User", Toast.LENGTH_SHORT).show();
Log.d("Uservalue", ""+value);
}
#Override
public void onCancelled(DatabaseError databaseError) { }
});
Related
In my Android app, I have a database repository to contact Firebase Realtime Database and a service layer with some methods. My SaveUserProfile method works but I keep getting a null pointer on my GetUserFromUid.
The 'user' object it returns is null and I don't know why. The node in my DB is called "users" (all lowercase) and I want to retrieve a user as a model via their userId and display the name and email onscreen.
Can anybody see where I'm going wrong?
My DbContext:
public class DbContext implements IDbContext {
User user = null;
Context context;
DatabaseReference databaseUsers = FirebaseDatabase.getInstance().getReference("users");
public DbContext(Context context){
super();
this.context = context;
}
#Override
public void AddUserAccount(User user1) {
databaseUsers.child(user1.userId).setValue(user1);
}
#Override
public User GetUserFromFirebase(String uid) {
databaseUsers.child(uid)
.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
user = dataSnapshot.getValue(User.class);
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
return user;
}
My DbService:
public class DbService implements IDbService {
//instance of DbContext for firebase handling
private DbContext dbContext;
public DbService(Context context){
super();
dbContext = new DbContext(context);
}
#Override
public User SaveUserProfile(User u) {
dbContext.AddUserAccount(u);
return u;
}
#Override
public User GetUserFromUid(String uid) {
User user = dbContext.GetUserFromFirebase(uid);
return user;
}
My User model:
public class User {
public String userId;
public String name;
public String email;
public String account;
//constructor required for calls to DataSnapshot.getValue(User.class)
public User(){
}
public User(String userId, String name, String email, String account) {
this.userId = userId;
this.name = name;
this.email = email;
this.account = account;
}
public String getUserId() {
return userId;
}
public void setUserId(String userId) {
this.userId = userId;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public String getAccount() {
return account;
}
public void setAccount(String account) {
this.account = account;
}
My activity where I want to display the users' details:
public class DetailsActivity extends AppCompatActivity {
//tag
private static final String TAG = DetailsActivity.class.getSimpleName();
//firebase auth
private FirebaseAuth mAuth;
//variables
private TextView inputName, inputEmail;
private DatabaseReference mFirebaseDatabase;
private String userId;
public String currentUserAccount;
public String teacherAccountNav = "Teacher";
public User userDetails;
#RequiresApi(api = Build.VERSION_CODES.KITKAT)
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_details);
inputName = findViewById(R.id.nameTextView);
inputEmail = findViewById(R.id.emailTextView);
FirebaseUser user = FirebaseAuth.getInstance().getCurrentUser();
assert user != null;
userId = user.getUid();
getUserDetails(userId);
inputName.setText(userDetails.name);
inputEmail.setText(userDetails.email);
}
public User getUserDetails(String uid){
DbService dbService = new DbService(this);
userDetails = dbService.GetUserFromUid(uid);
return userDetails;
}
EDITS BELOW
My callback:
public interface Callback {
void myResponseCallback(User user);
}
My EDITED DbContext:
public class DbContext implements IDbContext {
User user = null;
Context context;
DatabaseReference databaseUsers = FirebaseDatabase.getInstance().getReference("users");
public DbContext(Context context) {
this.context = context;
}
#Override
public void AddUserAccount(User user1) {
databaseUsers.child(user1.userId).setValue(user1);
}
#Override
public void GetUserFromFirebase(String uid, final Callback callback) {
databaseUsers.child(uid)
.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
user = dataSnapshot.getValue(User.class);
callback.myResponseCallback(user);
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
}
My EDITED DbService:
public class DbService implements IDbService {
//instance of DbContext for firebase handling
public DbContext dbContext;
public DbService(Context context){
super();
dbContext = new DbContext(context);
}
#Override
public User SaveUserProfile(User u) {
dbContext.AddUserAccount(u);
return u;
}
#Override
public User GetUserFromUid(String uid) {
final User[] user1 = {new User()};
dbContext.GetUserFromFirebase(uid, new Callback() {
#Override
public void myResponseCallback(User user) {
user1[0] = user;
}
});
return user1[0];
}
My EDITED Activity:
#RequiresApi(api = Build.VERSION_CODES.KITKAT)
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_details);
inputName = findViewById(R.id.nameTextView);
inputEmail = findViewById(R.id.emailTextView);
FirebaseDatabase mFirebaseInstance = FirebaseDatabase.getInstance();
//reference to 'users' node
mFirebaseDatabase = mFirebaseInstance.getReference("users");
FirebaseUser user = FirebaseAuth.getInstance().getCurrentUser();
assert user != null;
userId = user.getUid();
getUserFromFirebase(userId);
}
public void getUserFromFirebase(String uid){
userDetails = (new DbService(this)).GetUserFromUid(uid);
inputEmail.setText(userDetails.email);
inputName.setText(userDetails.name);
}
Debug BEFORE edits:
Debug AFTER edits:
As you can see from the debug, before the callback interface, userDetails was null. After the interface implementation, userDetails is not null but all of the object values are null. I don't know why this is as they are filled in the database. Any ideas?
this is a picture of firebase datathis is the image of log which i am getting in logcat
mDatabase=FirebaseDatabase.getInstance();
mRef=mDatabase.getReference("items").child("0").child("snippet");
mChildEventListner = new ChildEventListener() {
#Override
public void onChildAdded(#NonNull DataSnapshot dataSnapshot, #Nullable String s) {
for (DataSnapshot Snapshot : dataSnapshot.getChildren()) {
CategoriesModelClass user = dataSnapshot.getValue(CategoriesModelClass.class);
Log.d("kkk", "" + user);
title_description.add(user);
}
categoriesRecycleView.notifyDataSetChanged();
}
This is my code from activitymain and I don't know should I fire query for title and description or it it will fetch it from the for loop?
this is the code of my model class
public class CategoriesModelClass {
String title,description;
public CategoriesModelClass(){
}
public CategoriesModelClass(String title, String description) {
this.title = title;
this.description = description;
}
public String getTitle() {
return title;
}
public String getDescription() {
return description;
}
public void setTitle(String title) {
this.title = title;
}
public void setDescription(String description) {
this.description = description;
}
}
and i am try to set this data in my recycle view i need only title and description
To get the values of description and title, please use the following lines of code:
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference snippetRef = rootRef.child("items").child("0").child("snippet");
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
CategoriesModelClass user = dataSnapshot.getValue(CategoriesModelClass.class);
Log.d("kkk", "" + user.getTitle());
//Get the values out of the user object
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
Log.d("TAG", databaseError.getMessage()); //Don't ignore errors!
}
};
snippetRef.addListenerForSingleValueEvent(valueEventListener);
See, there is no need to loop over the snippet node, and this because we need to get the data according to type of object that is stored.
If there will be more than one items in the 0 node, then please use the following lines of code:
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference zeroRef = rootRef.child("items").child("0");
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot ds : dataSnapshot.getChildren()) {
CategoriesModelClass user = ds.getValue(CategoriesModelClass.class);
Log.d("kkk", "" + user.getTitle());
}
//Get the values out of the user object
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
Log.d("TAG", databaseError.getMessage()); //Don't ignore errors!
}
};
zero.addListenerForSingleValueEvent(valueEventListener);
First time working with Firebase realtime database I'm trying to read data from the database with Android application this is my first experience I'm sorry I'm used to working with MySQL so this JSON format seem to be complicated for me
I get the error No setter/field for found on class.
private FirebaseDatabase mDatabase = FirebaseDatabase.getInstance();
DatabaseReference mDbRef = mDatabase.getReference().child("users");
mDbRef.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
Users user = dataSnapshot.getValue(Users.class);
Log.d("result", "User name: " + user.getName() + ", email " + user.getEmail());
}
#Override
public void onCancelled(DatabaseError error) {
Log.w("error", "Failed to read value.", error.toException());
}
});
database example
and this my Users class
public class Users {
private String phone;
private String email;
private String name;
private String adresse;
private String ville;
private String zip;
public Users() {
}
public String getPhone() {
return phone;
}
public void setPhone(String phone) {
this.phone = phone;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getAdresse() {
return adresse;
}
public void setAdresse(String adresse) {
this.adresse = adresse;
}
public String getVille() {
return ville;
}
public void setVille(String ville) {
this.ville = ville;
}
public String getZip() {
return zip;
}
public void setZip(String zip) {
this.zip = zip;
}
}
I have attached an image for the struct of the database if anyone have any solution please help me
To solve this problem, you need to loop through entire users node using getChildren() method, like in the following lines of code:
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference usersRef = rootRef.child("users");
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot ds : dataSnapshot.getChildren()) {
Users users = ds.getValue(Users.class);
Log.d("result", "User name: " + user.getName() + ", email " + user.getEmail());
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
Log.d(TAG, databaseError.getMessage()); //Don't ignore errors!
}
};
usersRef.addListenerForSingleValueEvent(valueEventListener);
The result in your logcat will be the name and email of all users.
You should use ChildEventListener as your data is a list , if u use ValueEventListener then it will return the entire list of data as a single DataSnapshot which is not the recommended way.
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference usersRef = rootRef.child("users");
ChildEventListener childEventListener = new ChildEventListener() {
#Override
public void onChildAdded(DataSnapshot dataSnapshot, String previousChildName) {
Users user = dataSnapshot.getValue(Users.class);
Log.d("result", "User name: " + user.getName() + ", email " + user.getEmail());
}
#Override
public void onChildChanged(DataSnapshot dataSnapshot, String previousChildName) {
}
#Override
public void onChildRemoved(DataSnapshot dataSnapshot) {
}
#Override
public void onChildMoved(DataSnapshot dataSnapshot, String previousChildName) {
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
};
usersRef.addChildEventListener(childEventListener);
I am trying to get data from firebase, to show it in the TextView. Actually, I am new to android can anybody tell me what is the problem here is my code.
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference("https://videoanimation-a931e.firebaseio.com/");
auth = FirebaseAuth.getInstance();
String userId = auth.getCurrentUser().getUid();
DatabaseReference uidRef = rootRef.child("Person").child(userId);
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
User user = dataSnapshot.getValue(User.class);
if(user !=null) {
String name = user.getName();
String email = user.getEmail();
String designation = user.getDesignation();
textViewName.setText(name);
textViewEmail.setText(email);
textViewDesignation.setText(designation);
}else {
Toast.makeText(ProfileActivity.this, "user is null", Toast.LENGTH_SHORT).show();
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
};
uidRef.addListenerForSingleValueEvent(valueEventListener);
}
i dot know if my answer can help you, but please take a look at my snipshet code, this method how i get value firebase Realtime database child user value
//Getting Uid user
mAuth = FirebaseAuth.getInstance();
if (mAuth.getCurrentUser() != null) {
mUserRef = FirebaseDatabase.getInstance().getReference().child("Users").child(mAuth.getCurrentUser().getUid());
mUserRef.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
String name = ""+dataSnapshot.child("nama").getValue().toString();
String jabatan = ""+dataSnapshot.child("jabatan").getValue().toString();
String image = ""+dataSnapshot.child("image").getValue().toString();
display_name.setText(""+name);
display_address.setText(""+jabatan);
if (!image.equals("default") && image!= null){
Glide.with(getApplicationContext()).load(image).listener(new RequestListener<Drawable>() {
#Override
public boolean onLoadFailed(#Nullable GlideException e, Object model, Target<Drawable> target, boolean isFirstResource) {
return false;
}
#Override
public boolean onResourceReady(Drawable resource, Object model, Target<Drawable> target, DataSource dataSource, boolean isFirstResource) {
return false;
}
}).into(circleImageView);
}else {
}
mUserRef.child("role").addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
String srole = dataSnapshot.getValue().toString();
preferenceManager.simpanRole(srole);
setdashbourUI(preferenceManager.ambilRole());
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
full implement code you can check HERE !!
This fragment
User user = dataSnapshot.getValue(User.class);
try to change to this
User user = dataSnapshot.toObject(User.class);
And up use
private DatabaseReference mDatabase;
mDatabase = FirebaseDatabase.getInstance().getReference();
I would like to list the users who registered to the system.
MainPage:
List<User> users;
databaseReference = FirebaseDatabase.getInstance().getReference("Users");
databaseReference.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
if(dataSnapshot.exists())
{
for(DataSnapshot postSnapShot:dataSnapshot.getChildren())
{
User user = postSnapShot.getValue(User.class);
users.add(user);
customAdapter.notifyDataSetChanged();
}
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
Log.e("selam", "onCancelled: " + databaseError );
}
});
User Java Class
public class User {
private String email ="";
private String nickname="";
private String status="";
private String uid="";
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public String getNickname() {
return nickname;
}
public void setNickname(String nickname) {
this.nickname = nickname;
}
public String getStatus() {
return status;
}
public void setStatus(String status) {
this.status = status;
}
public String getUid() {
return uid;
}
public void setUid(String uid) {
this.uid = uid;
}
İmages
You get that NullPointerException because you haven't initialized your users list. To solve this, please use the following code:
databaseReference.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
if(dataSnapshot.exists())
{
List<User> users = new ArrayList<>(); //Initialize the list
for(DataSnapshot postSnapShot : dataSnapshot.getChildren())
{
User user = postSnapShot.child("userInfo").getValue(User.class);
users.add(user);
}
customAdapter.notifyDataSetChanged();
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
Log.e("selam", "onCancelled: " + databaseError );
}
});
Please also note, that I moved customAdapter.notifyDataSetChanged();, outside the for loop and I have also added .child("userInfo") call because there is an extra level in your database tree.